1. Field of the Invention
The disclosure taught herein relates generally to subsea operations on installing pipe to subsea equipment, and more specifically, relates to an installation method of installing flexible pipe with a subsea connector, utilizing a pull down system.
2. Description of the Related Art
Currently for subsea mining extraction, a vertical riser is deployed from a sea surface by a floating structure, such as a vessel. The top of this riser is maintained to a deck of the vessel and is deployed under the vessel by a moonpool or from the side of the vessel. A subsea pump is connected to the bottom of the vertical riser. A flexible pipe (or jumper) is connected between the subsea pump and a subsea miner. The miner can move on the seafloor in order to mine solids on the seafloor and thus beneficially use the flexibility of the flexible pipe. Usually, the bottom of the riser is connected to the subsea pump and a first portion of the jumper is connected to the pump. Then, the riser with the associated equipment is deployed vertically under the vessel with the pump and the jumper in the vertical position.
It would be advantageous to lower the subsea miner with a crane from the vessel to the seafloor and to position a second portion of the jumper vertically above the subsea miner to connect the jumper to the subsea miner and continue to deploy the riser. Also, it would be advantageous to connect the second portion of the jumper to the subsea miner under the vessel and deploy both of the first and second portions of the jumper subsea. However, without more, this desirable solution would introduce a high level of risk to damaging the jumper connections in trying to control or connect the pump and jumper with the subsea miner on the seafloor from top surface operations. This desirable solution would impose more risk, man hours, vessel down time, and inherently more associated costs.
Subsea equipment other than subsea miners have similar issues. For example, pipeline end terminals (PLET) that are designed to transfer liquids and other materials to further equipment require connections that fluidicly couple the PLET to pipes and other conduits. The expense of such making such subsea connections, and risk of damaging such connections presents challenges under present methods.
There remains a need for connecting pipe with subsea connections that utilizes little or no intervention from a top surface.